Aim: In cases of ventral hernia, in the presence of complications such as strangulation, a variety of intestinal bacteria can penetrate to peritoneal fluid and can cause peritonitis. However, these infections are rare in unstrangulated hernia cases. In this case report, it is emphasized that anaerobic bacteria and other bacteria can be isolated from patients with unstrangulated umbilical hernia to be cause of peritonitis. Case report:The 94-year-old female patient with unstrangulated ventral hernia was operated on as an emergency. The liquid that has accumulated in the hernia sac was taken for Gram stain and culture. Five ml peritoneal fluid was inoculated in the BACTEC plus Anaerobic F (Becton Dickinson-Maryland, USA) bottle. In addition, the fluid sample was inoculated on blood agar and EMB (eosin methylene blue) agar medium for aerobic isolation, and was inoculated on Schaedler agar medium (Oxoid, Hampshire, United Kingdom) for anaerobic isolation, and they was incubated at 37°C. Isolated facultative anaerobic bacteria were identified by using conventional methods; anaerobic bacterium was identified by using conventional methods, the API 20 a panels and An-Ident Discs tests.In the microbiological examination by Gram stain, no microorganism was observed. E. coli and Enterococcus spp. were identified as facultative anaerobic bacteria, and B. fragilis as anaerobic bacterium. After surgery of the patient, ceftriaxone and metronidazole were ordered. According to the culture results, ciprofloxacin was replaced by ceftriaxone in the treatment and the patient was discharged by healing. Conclusion:In patients with unstrangulated ventral hernia, anaerobic bacteria and other bacteria may be cause of peritonitis due to penetration of intestinal flora to peritoneal fluid. Isolation of Anaerobic